High-speed transmission of a large amount of data has become possible due to developments in wireless communication technology, such that terminal devices have been developed to perform not only a voice call function but also perform a video call function. A video call function indicates a function of transceiving an audio signal and a video signal among a plurality of terminal devices. When a video call starts, a terminal device may activate a camera, compress a video signal received from the outside, and transmit a compressed video signal to an opposite terminal device.
In a general case in which a terminal device performs a voice call function, a user of the terminal device transceives speech while capturing and transmitting an image of his/her own face. On the other hand, when the user of the terminal device captures and transmits an image of a surrounding environment and ambient audio, a user of an opposite terminal device experiences high-level noise compared to a general voice call. Because the terminal device uses a speech compression technology developed on the assumption that voice is input, when the terminal device attempts to compress and transmit non-voice audio, call quality may significantly deteriorate.
When the terminal device transmits voice signals of two or more users to an opposite terminal device, a user of the opposite terminal device experiences high-level noise. Because the terminal device uses a speech compression technology developed on the assumption that speech of one person located near a microphone of the terminal device is input, when two or more users simultaneously perform a video call, call quality may significantly deteriorate.